module count2bit(cnt, clk, res_, en);
    output [1:0] cnt; // the counter value
    reg [1:0] cnt;
    input clk, res_, en;
    reg [1:0] next_cnt; // the next state
    
    parameter S0=2'b00, // the states
    S1=2'b01,
    S2=2'b10,
    S3=2'b11;
    
    always @(posedge clk or negedge res_)
        if (res_ == 1'b0)
            cnt <= 2'b00;
        else
            cnt <= next_cnt;
    
    always @(en or cnt)
        case (cnt)
            S0: if (en == 1'b1) // full if-then-else implem.
                    next_cnt = S1;
                else
                    next_cnt = S0;
            S1: if (en == 1'b1) // the else path is not needed
                    next_cnt = S2;
            S2: next_cnt = (en == 1'b1) ? S3 : S2; // shorter
            S3: next_cnt = (en) ? S0 : S3; // even shorter
        endcase
endmodule


[ [ [ 'module',
      'count2bit',
      '(',
      [['cnt'], ['clk'], ['res_'], ['en']],
      ')',
      ';'],
    [ ['output', '[', '1', ':', '0', ']', 'cnt', ';'],
      ['reg', '[', '1', ':', '0', ']', ['cnt'], ';'],
      ['input', 'clk', 'res_', 'en', ';'],
      ['reg', '[', '1', ':', '0', ']', ['next_cnt'], ';'],
      [ 'parameter',
        ['S0', '=', "2 'b 00"],
        ['S1', '=', "2 'b 01"],
        ['S2', '=', "2 'b 10"],
        ['S3', '=', "2 'b 11"],
        ';'],
      [ 'always',
        ['@', '(', ['posedge', ['clk'], 'negedge', ['res_']], ')'],
        [ 'if',
          ['(', ['res_'], '==', "1 'b 0", ')'],
          [[['cnt'], '<=', "2 'b 00"], ';'],
          'else',
          [[['cnt'], '<=', ['next_cnt']], ';']]],
      [ 'always',
        ['@', '(', [['en'], ['cnt']], ')'],
        [ 'case',
          '(',
          ['cnt'],
          ')',
          ['S0'],
          ':',
          [ 'if',
            ['(', ['en'], '==', "1 'b 1", ')'],
            [[['next_cnt'], '=', ['S1']], ';'],
            'else',
            [[['next_cnt'], '=', ['S0']], ';']],
          ['S1'],
          ':',
          [ 'if',
            ['(', ['en'], '==', "1 'b 1", ')'],
            [[['next_cnt'], '=', ['S2']], ';']],
          ['S2'],
          ':',
          [ [ ['next_cnt'],
              '=',
              '(',
              [['en'], '==', "1 'b 1"],
              ')',
              '?',
              ['S3'],
              ':',
              ['S2']],
            ';'],
          ['S3'],
          ':',
          [ [['next_cnt'], '=', '(', [['en']], ')', '?', ['S0'], ':', ['S3']],
            ';'],
          'endcase']]],
    'endmodule']]